Thin film transistors called “TFT” are used in active matrix display devices such as liquid crystal display devices and organic electroluminescence (EL) display devices.
Thin film transistors having semiconductor layers made of silicon are typically used in commercially available display devices. In recent years, however, attention has been given to thin film transistors whose semiconductor layers can be formed by a liquid phase process. Organic thin film transistors having semiconductor layers made of an organic material and the like have particularly attracted attention. These thin film transistors whose semiconductor layers can be formed by a liquid phase process allow a flexible material with a low process temperature (e.g. a resin such as plastic) to be used as a substrate.
Thus, the use of thin film transistors (especially, organic thin film transistors) whose semiconductor layers can be formed by a liquid phase process enables production of a lighter, thinner, and more flexible electronic device than an electronic device including silicon thin film transistors. Proposals of using organic thin film transistors in next-generation display devices, electronic paper, and the like have been made accordingly.
For example, Patent Literature (PTL) 1 discloses a bottom-gate organic thin film transistor. The conventional organic thin film transistor includes: a gate electrode; a gate insulator; a pair of a source electrode and a drain electrode (source/drain electrode); a partition wall part having an opening above the gate electrode; and an organic semiconductor layer formed in the opening of the partition wall part by inkjet.
The organic thin film transistor having such a structure is used, for example, as a driver transistor or a switching transistor provided for each pixel in a TFT array substrate in which a plurality of pixels are arranged in a matrix. In the organic thin film transistor of each pixel, the source/drain electrode is extended to also function as wiring.